Our British Snails Part 2

_H. (Pomatia) pomatia._--Described earlier. Found in Hants, Suss.e.x, Kent, Surrey, Oxford, Gloucester, and Bedfordshire; but very local.

Elsewhere it may well be an escape from captivity, or the remains of an attempt (always unsuccessful) to establish a colony. Box Hill and Caterham are two good localities for Londoners. In Kent it has two centres, Charing and Sh.o.r.eham with their contiguous parishes, but there is a great gap between them, and it is absent from places on the same chalk ridge which are identical in soil and vegetation.

_H. (Cryptomphalus) aspersa._--The sub-generic name means that the umbilicus is hidden in adult sh.e.l.ls by a fold of the pillar lip; the specific name means sprinkled (with brown blotches); but it may be a slip of the pen, for _aspera_, or rough, from the rough s.h.a.greening of its surface. Five banded, like so many of the Helicidae, but usually the second and third band unite. No umbilicus. The variety _exalbida_ (chiefly found in Kent and the West) is straw colour and somewhat transparent. Commonly sold for food on the Continent as well as _pomatia_, which is cultivated in "snail-farms," but not native in Germany or Switzerland, and in France chiefly found in the coast departments. Insipid; but as nourishing as calf's-foot jelly. Fond of gardens (whence its common name), but not of gardeners. As most animals are marvellously gifted with a knowledge of what food to eat and what to avoid, it is curious that _aspersa_ will eat voraciously the leaves of the spindle-tree, though this soon poisons them. It is said also that they share with cows and horses the ignorance that the leaves of the yew should be avoided on pain of sickness or even of death.

_H. (Cepaea) nemoralis._--As already stated, this is the most brilliantly and variously coloured and diversely banded of all our English land sh.e.l.ls with the exception of its very close connection _H. (Tachea) hortensis_. It is happily very common, and so the attention of beginners should first be directed to this. Thrushes and mice are its great enemies, the former smashing it on some stone which may be found surrounded by the broken sh.e.l.ls. The "mouth" or peristome is normally black, the sh.e.l.l larger and stouter than _hortensis_, in which the mouth is white. When a white-mouthed _nemoralis_ or dark-mouthed _hortensis_ (both rare) is found, the shape of the internal flinty dart at once distinguishes them. In some places both live together: in most one is found and not the other. _Nemoralis_ is fond of sand-hills by the coast, but is chiefly a hedge-snail, and the edges of main roads are preferred because of the greater variety of food, because the traffic scares away their bird enemies, and because the dust gives them abundance of already prepared material for their sh.e.l.ls. When, however, the collector comes to a wayside cottage where fowls are kept he need not waste his time in looking for snails in the neighbouring hedge. The more the chicken industry extends and the more the Bird Protection Acts operates, the worse it is for collectors of snails. The banding is probably protective, as in the case of the tiger and the zebra, and renders the sh.e.l.l less visible.

_Helix (Cepaea) hortensis._--Rarely found in gardens in spite of its specific name. A hedge-snail. White forms not uncommon, though almost unknown in _nemoralis_. Though the weaker form, the coalescence of the five bands into one broad one is more common here than in _nemoralis_.

Also the variety with only one band, and that on the periphery, is very common in _nemoralis_ and rare in _hortensis_. It is more dependent on shade and moisture than its congener. Smells of garlic when immersed in boiling water to be killed. _Hortensis_ is a more northern, and _nemoralis_ a more southern, sh.e.l.l by origin and distribution. There are 89 possible band variations in any normally five-banded sh.e.l.l, and all have been noted in the case of _nemoralis_, but in _hortensis_ only 61. They are distinguished, for purposes of record and exchange, by numbers. Thus the type is 12345, the usual one-banded variety 00300, the common coalescence of the second and third band is 1(23)45, and when all bands unite (12345). The unicolourous or bandless variations would be 00000.

_H. (Arianta) arbustorum._--Local. Usually found in hedges and by ditches on chalk and limestone. Sh.e.l.l globose, brown or yellow, with a check or willow leaf pattern, and a single dark band on the periphery.

Lip strong and white. Animal usually nearly black. Very fond of moisture. Anatomically related to _A. lapicida_, but no external resemblance.

_Helix (Theba) cantiana._--First observed in Kent (where it is especially fine and abundant), whence its specific name, but generally dispersed in South and East England. A dull, creamy white sh.e.l.l with a pink tinge, sometimes becoming partially or wholly reddish.

_Helix (Theba) cartusiana_ (first noticed near a Carthusian monastery). Much resembles _cantiana_, but is much smaller and more smooth. Chiefly found on the downs of Kent and Suss.e.x. Used to be common on Deal sand-hills--now devastated by golf! The tint in this is brown, in the former red.

_H. (Hygromia) rufescens._--A flattish, dark brown sh.e.l.l, abundant in the south of England, and not rare elsewhere. Has a semi-lunar mouth with a white internal rib. In gardens seems to prefer violet beds.

_H. (Hygromia) hispida_, _i.e._ hairy.--These hairs are deciduous, and the hairless variety used to be considered a separate species under the name of _concinna_ (_i.e._ neat), but would now be the variety _depilata_, or bald. Broad and deep umbilicus. Common, except in Ireland. Usually a.s.sociates with _H. rufescens_ in moist places.

_H. (Hygromia) granulata_ is also hairy with white silky bristles.

Yellowish in colour. Sh.e.l.l thin. Local, but abundant where found. Its umbilicus is very small. It falls from its food plants at the least shake.

_H. (Hygromia) revelata._--Scantily haired. Globular thin sh.e.l.l. Pale green. Mainly found in Cornwall and South Devon. In cold or dry weather it buries itself rather deeply.

_H. (Hygromia) fusca._--Very thin, glossy, brown sh.e.l.l. Local. Hardy, and even active in frost. Chiefly found on nettles, which many sh.e.l.ls like as food, though avoiding the commonly a.s.sociated h.o.r.ehound.

_H. (Euparypha) pisana._--First noticed at Pisa. Somewhat like _Helicella virgata_, but larger, sub-globular, and solid sh.e.l.l, yellowish-white with dark lines or bands. Aperture or mouth yellowish or rosy. Most common in Portugal and Morocco, and all round the Mediterranean, dry places, especially near the sea. In England chiefly confined to Tenby and other parts of Pembrokeshire; also in the Channel Islands. Varies much in tint and markings. Swarms where found; it loves sun and heat. Seems to lend itself better to colonization than most species.

_H. (Helicella) itala._--So named by Linnaeus, who probably received it first from Italy. Sh.e.l.l almost circular, flat. Umbilicus very large and open. Common on heaths and downs, especially near the sea.

_H. (Candidula) caperata._--(The specific name means wrinkled, like a goat's horn.) Careless of heat or cold. Distinguished from the young of _H. virgata_ by being more depressed, having a larger umbilicus, regular and strong striation, and round mouth with white internal rib.

Found under stones and on gra.s.s. Common.

[Ill.u.s.tration: _Helicella virgata_ at rest on thistle, natural size.]

_H. (Heliomanes) virgata_ (_i.e._ striped).--A very variable sh.e.l.l.

See the ill.u.s.tration above of some at rest on thistles. Local, but very abundant where found. Whitish sh.e.l.l with dark bands, but a yellowish and a white variety usually is found with the type. The most beautiful variety, _radiata_, is chiefly found in Romney Marsh, and from Hythe to Rye.

_H. (Turricola) terrestris._--A Mediterranean species, well established since 1890, in one spot near Dover. A pyramidal sh.e.l.l, greyish, with one dark band on each whorl.

_H. (Cochlicella) barbara_ (_i.e._ foreign).--Long, conical, whitish, with one dark band. By the sea-coast. In shape somewhat like a Buliminus.

We come now to the Pupa family and its genus Buliminus and its sub-genus Ena. It is represented by:--

_Ena montana._--A local and southern sh.e.l.l, conical, slightly glossy, brown. Lip white and deflected. Commonly found on the holes of smooth-barked trees, and it closely resembles the small k.n.o.bs on beech trunks.

_Ena obscura._--Like the former, but much smaller, and found nearly everywhere in England and Wales. Found in hedgebanks, or on beech trunks. Its specific name is derived from its habit of covering itself with a coating of earth, and so becoming inconspicuous.

The plate on p. 47, gives figures of some of our smaller sh.e.l.ls, enlarged in most cases so that their distinguishing marks can be seen.

The upright line by the side of each figure gives its actual height.

The sh.e.l.ls as numbered are _Helix rupestris_, _H. pygmaea_, _H.

pulch.e.l.la_, _H. lapicida_, _H. obvoluta_, _H. terrestris_, _H.

barbara_, _Ena montana_, _Ena obscura_, _Pupa secale_, _P. anglica_, _P. cylindracea_, _P. muscorum_, _Vertigo antivertigo_, _V.

moulinsiana_, _V. pygmaea_, _V. alpestris_, _V. substriata_, _V.

pusilla_, _V. angustior_, _V. edentula_, and _V. minutissima_. Without a magnifying gla.s.s it will be seen that it would be very hard to distinguish some of the minute sh.e.l.ls, but this enlargement enables us to see the characteristic denticles in the mouth, and the presence or absence of striations on the sh.e.l.l.

[Ill.u.s.tration: Some of our smaller sh.e.l.ls. Actual size indicated by the upright line.]

_Pupa (Abida) secale_ is named from the Latin for rye, a grain of which the sh.e.l.l more or less resembles. Conical, brown, mouth horseshoe-shaped with eight white denticles. Our largest Pupa. Local, but abundant where found. Prefers calcareous rocks or woods.

_Pupa (Lauria) anglica._--Small, ovate, purplish in colour; mouth like that of _secale_. Lives in moss, mainly in the north of Britain.

_Pupa (Lauria) cylindracea._--Small, cylindrical, paler than the last; thick and reflected white lip with one denticle. Abundant. On stones, in moss, under leaves and bark.

_Pupa (Jaminia) muscorum._--Common, especially on sandy soils near the sea. Mouth nearly circular, whereas in the two former species it is horseshoe-shaped. The lip is thin and not reflected.

The genus Vertigo (_i.e._ twisted, the Latin equivalent of the Greek Helix) contains sh.e.l.ls even smaller than the Pupae, about the size of a pin's head.

_Vertigo (Alaea) antivertigo_ (_i.e._ not reversed or sinistral, as are _V. pusilla_ and _V. angustior_). Semi-transparent, glossy, horn-colour, with denticles (as have all except _V. edentula_ and _V.

minutissima_). Found in nearly all counties in moist places.

_Vertigo (Alaea) moulinsiana._--Our largest species, though only 2-1/3 millimetres in height. Mainly in marshy places. Not common.

_Vertigo (Alaea) alpestris._--Rare and local, chiefly northern. Nearly transparent sh.e.l.l.

_Vertigo (Alaea) pygmaea._--Common, and often in colonies at roots of gra.s.s and under stones and logs. Not confined to moist places.

_Vertigo (Alaea) substriata._--Local. Strongly striated.

_Vertigo (Vertilla) pusilla._--Sinistral, as is also

_Vertigo (Vertilla) angustior._--Both species rare and local. The former is the larger and broader. In the former the last whorl is broadest, in the latter the penultimate. In the former the mouth is semi-oval, in the latter triangular. In the former the outer lip is very slightly, in the latter very deeply contracted. The former has 6 to 7 teeth, the latter 4 to 5.

_Vertigo (Sphyradium) edentula_ is dextral and without denticles.

Perhaps the most common _Vertigo_. Partial to bracken.

_Vertigo (Isthmia) minutissima._--Dextral and without denticles.

Smaller, narrower, and more strongly striated than edentula, but rarer. All the Pupae should be examined with a magnifier.

_Balea perversa_ (_i.e._ sinistral) is a much larger sh.e.l.l belonging to the Clausilia family. Thin, dark horn-colour, semi-transparent, glossy, 7 to 8 whorls, local, but abundant where found. Chiefly found on trees.

_Clausilia (Pirostoma) bidentata._--All our British clausilias are sinistral. The clausilium (little door) is an internal contrivance fastened to the pillar of the sh.e.l.l (whereas an operculum is attached to the body of a mollusc) by an elastic ligament to protect it against insect enemies when the animal withdraws. _Bidentata_ has two denticles, fusiform and reddish-brown, as are all. Very common on walls and trees.

_Clausilia (Pirostoma) rolphii._--Rare and local. Almost subterranean in habit. More coa.r.s.ely striated than the last. The upper whorls nearly of the same breadth, forming a short cylinder.

_Clausilia (Alinda) biplicata._--Very local. Chiefly on Thames willows. Larger than the two former, and streaked with white.

_Clausilia (Marpessa) laminata._--Much like the former, but widely distributed. Usually found on beech and ash trees, and on limestone rocks. Smooth and glossy.